Carrier route record

DLLAS→BOS

Delta Air Lines · Las Vegas to Boston

Flights: 593
Period: July 2025 to June 2026
Share of route: 36%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on LAS to BOS lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 593 flights, with a median arrival 7 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on LAS to BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.5%

Arrivals under 15 minutes late, of 584 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

1.52%

National rate is 1.81%

Whole route

76.4%

Every carrier on LAS to BOS, 1,639 flights

These figures cover 593 flights between July 2025 and June 2026. Beyond the headline rate, 9.6% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Delta against every carrier on LAS to BOS

Delta flew 593 of the 1,639 flights on LAS to BOS, about 36% of it. Its 76.5% on time is about level with the route as a whole at 76.4%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 76.5% to JetBlue at 76.3%.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on LAS to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	593	76.5%	71 min	1.52%	B
JetBlue Airways	1,046	76.3%	81 min	1.24%	B

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am107 flights66.4%
11am–2pm258 flights75.3%
2pm–5pm4 flights—
5pm–8pm—
8pm–5am224 flights83.0%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

The overnight block holds up unusually well at 83.0% on time across 224 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 11am–2pm window is the busiest, with 258 flights scheduled in it.

Across the year

Delta on LAS to BOS through the year

Darker means more delays. Figures are on-time percentages.June best, October worst

Delays peak in October, when the on-time rate falls to 57.4%. June is the strongest month at 83.9%. Moving a flexible trip across that boundary buys 27 points. March was the busiest month here, with 61 flights.

Across the week, Saturday is the strongest day at 89.9% on time and Sunday the weakest at 69.7%. 20 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. National Airspace System accounts for 45% of the 9,780 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
45%
Carrier
26%
Late-arriving aircraft
25%
Extreme weather
3%

45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 4,401 minutes out of 9,780, against a national NAS share of 21%. The split is drawn from 9,780 reported delay minutes.

Cancellations sit at 1.52% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.6% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

At 2,381 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg runs 77.9% on time across 593 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 593 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Delta on LAS to BOS

Put together: treat all of this as provisional. 593 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 76.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 584 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures